Most formations bearing hydrocarbons simultaneously produce an oil phase, a gas phase and an aqueous phase, usually brine. Several wells can be tied together through a gathering line into a separation or processing plant, sometimes comprising just a simple tank, where initial gravity separation of water, oil and gas occurs. Theoretically, gas is taken from the top, water and sediments are drawn from the bottom, and the oil is drawn from the middle of the mixture. In practice, such separations have generally involved the direct heating of the hydrocarbon feed to achieve better separation of the three phases (the gas phase, the lighter hydrocarbon liquid or oil, and the heavier aqueous liquid). Unfortunately, when using conventional systems for separating the three phases, it can be difficult and costly to meet vapor pressure specifications. Accordingly, new techniques for better meeting vapor pressure specifications are of interest in the industry.